This invention relates to a power transmitting device for a marine propulsion unit and more particularly to an improved construction for transmitting the driving thrust from a propeller shaft to the lower housing of such a unit.
In marine propulsion units, there is normally provided a lower unit that comprises an outer casing which defines a cavity in which a driven shaft is journaled. The driven shaft drives a propulsion unit such as a propeller for propelling the associated watercraft through a body of water. Normally, the driven shaft is supported within a bearing carrier that is inserted into an opening formed in the rear of the lower unit housing and which opens into the cavity. Frequently, the driving thrust as well as the rotational support for the driven shaft are transmitted from this shaft to the watercraft through the bearing carrier and its cooperation with the lower unit housing. Normally, the cavity in which the driven shaft is supported also contains a forward, neutral, reverse transmission for selectively driving the watercraft in forward or reverse directions.
It is the general practice, when the driving thrust is transmitted to the lower unit housing from the bearing carrier to have the bearing carrier formed with a forwardly facing shoulder that engages a shoulder on the lower unit around the cavity. This thrust transferring engagement is normally positioned in close proximity to the forward, neutral, reverse transmission. As a result, if large driving thrusts are to be transmitted, the bearing surfaces must have substantial area and this tends to increase the overall dimension of the forward portion of the lower unit casing. Such increases in size are, however, undesirable because this increases the drag on the lower unit and the power required to move it through the water.
It is, therefore, a principal object of this invention to provide an improved arrangement for transmitting driving thrusts to the lower unit of a marine propulsion device.
It is a further object of this invention to provide a thrust transmitting arrangement for the bearing carrier of a marine propulsion lower unit that permits large bearing areas while, at the same time, permitting a compact and streamlined configuration.